Physicians' Desk Reference (please see entry to physicians' desk reference). Pdr less frequently stands for postdelivery room. ... (12 Dec 1998) ... Found on http://www.encyclo.co.uk/local/20973
a photodissociation region or photon-dominated region (both terms are used synonymously); a region in the neutral ISM in which far-ultraviolet photons dominate the heating and chemistry Found on http://www.translationdirectory.com/glossaries/glossary142.htm